Lecture 18: Cryosphere 2 Flashcards
Where does deposition of the the stuff that glaciers erode occur?
At the base margins of the glacier
What is Till?
The poorly sorted sediment left behind by glaciers
When can till be redeposited as out as?
If it is reworked by meltwater beyond the terminus of the glacier
How can Glaciers cause weathering of underlying bedrock?
With freeze thaw cycles
What are Moraines?
Ridgid accumulations of till that form as a glacier advances and retreats
What are the 3 types of Moraines?
- Medial moraines
- Terminal moraines
- Lateral moraines
Where do Medial Moraines form?
At the margin where two glaciers meet
Where do Terminal Moraines form and what do they mark?
At the terminus of a glacier and marks its furthest advance
What are Lateral Moraines?
A type of end moraine that forms at the sides of a glacier
What are the two types of end moraines?
Terminal Moraines and Lateral moraines
What is a Proglacial lake?
A lake that is at the toe of a glacier
What are Drumlins?
Elongated and asymmetrical hills that form near the terminus of glaciers by the action of glacial ice on underlying unconsolidated sediments
What is the direction of ice flow of a drumlin?
The steep side toward the shallow side of the drumlin
What are Eskers?
Ridges of well sorted sand and gravel that are formed by rivers flowing beneath glacial ice
What are Kettles?
Closed basins formed by the melting away of mass of underlying glacial ice
What are Kames?
Piles of sand and gravel that were accumulated in streams and lakes on top of glacial ice and are deposited on land surface when the glacier retreats
When do Proglacial lakes form?
When the glacier is melting and retreating
What is Permafrost?
Permanently frozen ground that contains ice that froze during past glaciation
Where is Permafrost thickest?
Areas that were exposed for long periods to colder air temperatures
What does permafrost protect?
Massive amounts of carbon from degradation by microbes to form greenhouse gases
What is the Active Layer of Permafrost?
The layer that sits on top and melts in the summer
What causes patterned grounds?
The cyclic freezing and thawing cycles each year
What are pingos?
Small hills that form from the freezing and thawing cycles
When does Sea Ice form?
When air temperature falls below the freezing sea point of seawater
